In the recovery of metals from metal ores, it is of course highly desirable to recover as much of the metal as is economically feasible from the ore.
In typical copper solvent extraction circuits copper recovery is about 90% where all of the raffinate (stripped aqueous acid leach solution) is recycled back to the leaching step for leaching the copper values from the copper ore.
However, in some plants using a copper extraction circuit a raffinate bleed must be removed to control the build up of impurities or to recover some other valuable metal such as cobalt. There are also plants where some of the raffinate recycled to the leaching step is lost, e.g. in agitation leach plants.
In the above plants it is desirable and even essential to recover a very high percentage of copper from the raffinate bleed stream and/or the raffinate used in recycling.
Several methods have been proposed to accomplish this, but such methods, e.g., acid neutralization of the bleed stream or high organic phase to aqueous phase ratios are not economically feasible.
There is accordingly, a strong need for a simple and economical process for reducing the concentration of copper in the raffinate or in the raffinate bleed stream, especially where a high copper content is present in the copper-pregnant acid leach solution.
The present inventor has discovered such a process.